根据没有比较器的成员变量的顺序对对象进行排序

Question

Say I have an object

Person
  private int age;
  private String name;

And I want to sort them automatically using something like Arrays.sort() such that low ages come before high ages.

A common way to do this is with a comparator, but I with so many useful utility functions out there, is there a cleaner way to do this?

Answer 1

使您的班级实现Comparable 。

Answer 2

lambdaj的示例解决了您的用例：

List<Person> sortedByAgePersons = sort(persons, on(Person.class).getAge());

Answer 3

Using Java 8 with Lambda:

personList.sort((p1, p2) -> Integer.compare(p1.age, p2.age));

or

Collections.sort(personList, (p1, p2) -> Integer.compare(p1.age, p2.age));

Answer 4

Mistakes were made

You can also implement the interface Comparable and override the compareTo(...) method.

These ways to not guarentee it will be cleaner, but they are just different ways to compare. Using Comparator is only useful when you want to order objects in such a way that does not follow it's natural order.